FIRST PHASE OF LUNAR EXPLORATION COMPLETED:

Mission to Fra Mauro

Whether any Americans were going to Mars in this century or not, the
crew of Apollo 13 - Jim Lovell, Ken Mattingly, and Fred Haise - were
going to the moon, and they were too busy preparing for that mission to
worry about anything more spectacular. Their Saturn V was trundled out
to launch complex 39A on December 15, 1969, anticipating launch on March
12, 1970.78 On January 8, however,
Headquarters announced that Apollo 13 had been rescheduled for April 11
to allow more detailed analysis of specific plans.79

The target for Apollo 13 was a spot some 180 kilometers (112 miles) east
of Apollo 12's landing site, just north of the crater Fra Mauro. The
mission's primary task was to sample the geologic unit called the Fra
Mauro Formation, which covers a large area around the Imbrium basin. The
Fra Mauro Formation was generally believed to consist of material
ejected when Imbrium, one of the largest impact basins on the moon, was
formed. Scientists hoped that samples would allow them to date the
"Imbrian event," which would establish the time relationships
of related and adjacent features. Finally, they expected that the Fra
Mauro site would provide samples that came from deep within the moon,
excavated by the Imbrian event.80 The
mission would also emplace a second set of lunar surface instruments,
differing from those flown on Apollo 12; a heat-flow experiment and a
charged-particle environment detector were substituted for the solar
wind spectrometer, the magnetometer, and the suprathermal ion detector.
A second calibration of the lunar seismometers was to be accomplished by
crashing the Saturn V's third stage at a preselected location on the
moon.81

Preparations for the launch proceeded without major problems through
February and March. Three days before launch, Jack Swigert took Ken
Mattingly's place as command module pilot, after the prime crew had been
exposed to German measles and Mattingly was found to have no immunity.
Apollo 13 lifted off on schedule at 2:13 p.m. Eastern Standard Time on
April 11, and for two days operations were routine; Capcom remarked at
one point that flight controllers were bored to tears. A few hours
later, however, an oxygen tank in the service module ruptured, depriving
the spacecraft of most of its electrical power and oxygen, and the
mission had to be aborted. Only a heroic effort of real-time
improvisation by mission operations teams saved the crew.82

Almost lost in the drama of the mission was the one piece of scientific
information that Apollo 13 was able to provide. Shortly after command
module pilot Jack Swigert had extracted the lunar module from atop the
S-IVB stage, ground controllers fired the auxiliary propulsion system on
the big rocket, putting it on a course to crash into the moon. Three
days later the 30,700-pound (13,925 kilogram) hulk struck the lunar
surface at 5,600 miles per hour (2.5 kilometers per second) some 74
miles (119 kilometers) west-northwest of the Apollo 12 landing site,
releasing energy estimated as equivalent to the explosion of 7.7 tons
(7,000 kilograms) of TNT. Half a minute later the passive seismometer
left by Apollo 12 recorded the onset of vibrations that persisted for
more than four hours. Another instrument, the lunar ionosphere detector,
sensed a gas cloud that arrived a few seconds before the seismic signal
and lasted for more than a minute. Seismologists were baffled by the
moon's response to shock, but welcomed the new means of generating
data.83

In the year that it took to discover and correct the cause of the Apollo
13 failure, the scope of the remaining missions was altered. Apollo 14
would visit the site intended for exploration by Apollo 13, but it would
go there as the last of the intermediate exploration missions. The
flights that remained would stretch the capabilities of the Apollo
systems virtually to their limits, providing longer visits to the lunar
surface and increased mobility for the astronauts. Unfortunately for
lunar science, two missions were to be cut from an already minimal
program.

82. The best account of Apollo 13 is
that of Henry S. F. Cooper, 13: The Flight That Failed (New
York: Dial Press, 1973), a taut narrative that captures the flavor of
the entire mission. For a first-person account by a participant, see
mission commander James A. Lovell's chapter, "Houston, We've Had A
Problem," in Apollo Expeditions to the Moon, Edgar M.
Cortright, ed., NASA SP-350 (Washington, 1975). A brief summary of the
mission and the investigation is given in Benson and Faherty,
Moonport, pp. 489-94. Headquarters' Public Affairs Office
prepared a 25-page booklet on the flight, "Houston, we've got a
problem," NASA EP- 76 (Washington, 1970). A concise summary of the
constraints faced by flight controllers and the rationale for the
real-time decisions made during Apollo 13 was presented by Glynn S.
Lunney, one of 13's flight directors, as AIAA Paper No. 70-1260,
"Discussion of Several Problem Areas During the Apollo 13
Operation," at the AIAA 7th Annual Meeting and Technical Display,
Houston, Oct. 19-22, 1970. The Report of the Apollo 13 Review
Board, a summary volume and eight technical appendices, was
released two months after the accident. It contains full technical
details of the causes of the accident as deduced from inflight
telemetry, the history of the faulty tank, and tests performed to
support the investigation. Board chairman Edgar M. Cortright presented
the board's findings to the House space committee on June 16, 1970; see
House, The Apollo 13 Accident, hearings before the
Committee on Science and Astronautics, 91/2, June 16, 1970.